Conduit assemblies for heat exchangers and the like

ABSTRACT

A heat exchanger for a sanitary shower or the like includes a primary flow conduit, and secondary flow conduit sections, each conduit section having a substantially flat wall spaced from and aligned with an adjacent surface of the primary conduit so as to avoid accumulation of dirt. The secondary conduits may have internal walls and a mesh may be provided for spacing conduit surfaces.

BACKGROUND OF THE INVENTION

This invention relates to conduit assemblies for heat exchangers and thelike. It also relates to heat exchangers and sanitary apparatus such asshower systems containing heat exchangers in drainage paths thereof.

This invention is particularly but not exclusively applicable in devicesor components for heat exchange between fluids in general and inparticular for heat exchange between two liquids flowing under disparateheads of pressure within constrained spaces, particularly for therecovery of heat from waste water draining from a sanitary shower, suchas is described in WO2009/101161 (Gilbert), which is entirelyincorporated herein by reference.

That document discloses a primary flow conduit containing secondaryconduit sections. The first fluid conduit has formations in its surfaceadjacent the secondary conduit sections and corresponding thereto inshape. This may provide recesses for trapped air or make air pocketswhich interfere with optimal fluid flow distribution or whichnecessitate an elaborate means of venting. Dirt (or silt) may accumulateover time in gullies, deposited out of suspension and that may interferewith optimal fluid flow. Cleaning or rinsing manually may be difficult.The apparatus may be technically demanding or complicated to fabricatewith the necessary precision, positional stability and be susceptible todisturbances in the uniformity of spacing between the heat-exchangingand enclosing primary conduit surfaces.

The present invention aims to alleviate at least to a certain extent theproblems of the prior art.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided athermally conductive conduit assembly being mountable in a primary(fluid) flow conduit of a heat exchanger or the like, the conduitassembly including two or more series of elongate conduit sectionscomprising a first and second series having the conduit sections thereofarranged next to one another such that each series extends in a seriesdirection which is generally transverse to the conduit sections, eachconduit section in at least the first series having at least a portionalong the length thereof which has a cross section having on a wide sideof the conduit portion a substantially flat first wall which issubstantially aligned with the series direction, the cross section alsoincluding a protruding wall formation in the conduit portion extending(protruding) towards a corner (angle or vertex) on a narrow side of theconduit portion located opposite the wide side (being it's counterpart)and being internested (interposed) between conduit sections of anotherinternesting series, with the substantially straight (flat) wallsubstantially coincident with a general (net) flow direction of saidprimary flow conduit. The narrow side of the said portions of conduitsections comprise an elongated convex surface (ridge), so the term“corner” used in defining the first aspect refers to this ridge and thecorresponding angle that the protruding wall formation makes in crosssection perspective.

The conduit assembly described hereinabove may thus be considered to bea secondary flow conduit for the transfer of heat between a secondaryfluid flowing therein and a primary fluid which the primary flow conduitof the heat exchanger (or like) conducts to flow therein. Preferably,the secondary fluid flows through a sequence (succession) of conduitsections of the conduit assembly along one or more flowpaths so as toprovide a counterflow heat exchange arrangement. Thus a further aspectof the invention provides a heat exchanger assembly which comprises aconduit assembly as set out in the first aspect which is mounted insidea primary flow conduit which has a general flow direction therethroughwhich is coincident with the substantially flat wall, the conduitassembly and the primary flow conduit being arranged for heat transferbetween respective fluids therein.

According to a further aspect of the invention there is provided a heatexchanger assembly having a primary flow conduit having a general flowdirection therethrough, and a conduit assembly mounted in the primaryflow conduit, the conduit assembly including first and second series ofelongate conduit sections, each series having the conduit sectionsthereof arranged next to one another in rows extending in a directiongenerally transverse to the conduit sections and coincident with thegeneral flow direction through the primary conduit, each conduit sectionin at least the first series having at least a portion along the lengththereof which has a substantially flat wall which is substantially inline with a substantially flat wall of one or more adjacent conduitsections in the same series (row), in the general (net) flow directionthrough (i.e. of) the primary flow conduit.

The primary conduit has an internal wall surface spaced from andsubstantially aligned with the substantially flat wall. Said internalwall surface may be substantially flat and parallel to saidsubstantially flat walls of a plurality of said conduit sections in asaid series which is adjacent to the internal wall surface.

A second side of a conduit section joins one (elongated) edge of thewide side to one (elongated) edge of the narrow side, whilst a thirdside of a conduit section joins the other (elongated) edge of the wideside to the other (elongated) edge of the narrow side.

According to a further aspect of the invention a conduit assembly isprovided wherein the conduit sections of the first and second serieshave a second and a third side with external walls thereof shaped andarranged in such a way that second side walls of the first seriescomplement the third side walls of the second series, and second sidewalls of the second series complement the third side walls of the firstseries so as to generally provide a substantially consistent gap for thepassageway there between of a layer of fluid having generally athickness which is not substantially varying thereat.

A number of features will now be described which may be optionallyincluded in embodiments in accordance with any one or more of the aboveaspects of the invention:

Each conduit may have a protruding wall portion which extends towardsthe other of the first and second series. That is, the first and secondseries have general orientations opposing (facing) one another, theorientation of each being in common with the orientations of theprotruding formation with respect to the wide side (first wall) of eachof their respective conduit sections (e.g. up vs. down, left vs. right,inward vs. outward). Conduit sections of the first series are preferablyinternested with conduit sections of the second series.

The protruding wall portion may be internested between conduit sectionsof the second series or another series of elongated conduits.

That is, the narrow sides of the first series' conduit sections arecloser than the wide sides to the wide sides of the second series'conduit sections, and vice versa (for those of the second series).

The conduit sections may be straight, or substantially straight.Alternatively, the conduit sections may be curved, in which case theymay be arranged in a spiral. In either case, the wide sides of theconduit sections of each series may be substantially in line, so as tofollow (or be tangential with) a line, which may be straight or gentlycurved, as viewed on a cross section of the said conduit sections.

The protruding wall portion may comprise two generally flat wallportions such that said cross section is substantially triangular. Theprotruding wall portion may be substantially symmetrical about a linesubstantially perpendicular to the substantially flat first wall.

The conduit sections in the other series may each have a cross sectionthe same as the cross section of the first series. The conduit sectionsof the first series may be internested between sections of the secondseries wherein each conduit section of the second series may have atleast a portion along the length thereof which has a cross sectionhaving on a wide side of the conduit portion a substantially straight(flat) first wall which is substantially aligned with the seriesdirection, the cross section also including a protruding wall formationin the conduit portion extending (or protruding) towards a corner(including an angle or vertex) on a narrow side of the conduit portionlocated opposite the wide side (being a counterpart thereof) and beinginternested between conduit sections of the first series, with thesubstantially straight (or flat) wall substantially coincident with ageneral (or net) flow direction of said primary flow conduit and/orsubstantially in line with a substantially flat wall of one or moreadjacent conduit sections in the second series (or row).

Said conduit sections may have internal walls extending therealong. Theinternal walls may extend fully across an inside of said sections todivide the interior of said sections into a plurality of conduit pathswithin each said conduit section. The internal walls may provide thermalbridging from positions within said conduit sections to exterior wallsthereof and may provide enhanced structural stability to the saidconduit sections.

A further aspect of the invention provides a conduit assembly for a heatexchanger which comprises an elongate conduit section which has aninternal wall extending therealong and arranged to act as a heat flowbridge from fluid in the conduit section to an external wall of theconduit section.

Each conduit may be extruded and of constant cross section therealong.

A conduit assembly may have one or more components preferably made ofplastic or resin which interconnect thermally conductive conduitsections at their ends.

A further aspect of the invention provides a conduit assembly mounted ina primary conduit having an adjacent internal wall portion that isspaced from and substantially aligned with the substantially flat wallof a thermally conductive conduit section.

Preferably the primary conduit has one or more portions of internalwall, which are substantially flat and parallel to the substantiallyflat wall of a plurality of thermally conductive conduit sections in thefirst and/or second series of the conduit assembly, which are adjacentto the said internal wall. A further aspect of the invention provides aconduit assembly for a heat exchanger which includes at least twoadjacent conduit surfaces arranged for fluid flow therepast in a fluidflow direction, and at least one flexible elongate spacing memberarranged to be located between the conduit surfaces to establish orstabilise a defined space therebetween.

The flexible elongate spacing member may be part of a mesh, the meshincluding a plurality of said flexible elongate spacing members, whichare interconnected by joining members.

At least one said flexible elongate member may be generally aligned witha said fluid flow direction.

Said joining members may be elongate lengths of material, in which casethey may be thinner than said at least one flexible elongate spacingmember.

Said flexible elongate members in some preferred embodiments may becords, strings or straps.

Said joining members in some preferred embodiments may be cords, stringsor straps.

A further aspect of the invention provides a heat exchanger assembly inwhich the primary flow conduit and conduit sections are mutuallyarranged for counterflow heat exchange generally between flows passingthrough the respective primary conduit and thermally conductive conduitsections.

In embodiments of the invention the substantially flat walls of theconduit sections of the conduit assembly and/or the primary flow conduitare generally horizontally arranged.

In other embodiments thermally conductive conduit sections can be madeprincipally from copper, aluminium or an alloy comprising substantiallyone of these metals, such as brass.

A further aspect of the invention provides a sanitary assembly such as ashower facility, which includes an assembly in accordance with anyprevious aspect of the invention. A further aspect of the inventionprovides a heat transfer conduit formation comprising pairs of generallylinear series of sections of said conduit. The sections have likeformation and orientation to one another, and each section in a saidseries is aligned with or consistently offset from the next in the sameseries and having an outer surface including or consisting of threesides. The surface(s) of one side are substantially flat and in asubstantially co-planar or co-linear arrangement with surface(s) of atleast one other section in the same series, the two series being in asubstantially parallel, near co-planar or co-linear and inverselyorientated arrangement with their respective conduit sectionsinternested with one another and spaced apart by a generally constantoffset distance.

The sides may be joined by corners or sections, which may be sharp,rounded or beveled. The sides other than the substantially flat side maybe flat, may have varying curvatures or may be of varied curvature.

Sides of the conduit sections other than the substantially flat side maybe substantially symmetrical about a line normal to the substantiallyflat side.

Surfaces of a second side of each section may correspond inversely inshape to surfaces of a third side of said conduit sections.

The conduit sections may have a cross section, which is triangular.Alternatively, the cross section may be at least partly: trapezoidal,shaped like the profile of a wide-rimmed bell or hat, sinusoidal, shapedlike the profile of a shark fin, or having one outwardly convex sideadjacent an outwardly concave side.

The conduit sections may have internal walls extending longitudinallywhich extend thereacross internally.

The conduit sections may be formed from various materials, including oneor more of copper, copper alloy such as bronze or brass, stainlesssteel, aluminium, aluminium alloy, or another metallic or other type ofalloy.

The conduit sections may be arranged as a succession of convolutingloops or loops that may form a flat, conical or cylindrical spiral ofany shape, the axis of rotation of which may be orientated vertically(or otherwise, such as horizontally), whereby each loop may form a pairwith an adjacent loop of conduit section in an adjacent series. Theloops may be arranged extending generally horizontally.

The conduit formation may be arranged for heat exchange with a primaryconduit of a heat exchanger for heat exchange between a first fluid inthe primary conduit flowing substantially as layers over the outersurfaces of said conduit formation. The flow in the primary conduit maybe transverse or oblique to the direction of a second fluid flowingalong and within the said conduit formation. The heat exchanger may bearranged for heat to flow from the first fluid to the second fluid. Theheat exchanger may be arranged with the conduit formation located insidethe primary conduit. Overall, the heat exchanger may be a counter-flowheat exchanger.

The shape of adjacent sections of said conduit formation and/or spacingbetween them may vary incrementally along a said series, therebygradually varying the thickness of the flowing first fluid layers in theprimary conduit so as to regulate overall the resistance to first fluidflow.

The said conduit sections may be joined to one another by sections ofjoining conduit made of plastic, resin, rubber or similar material. Thesections of joining conduit may be mutually interconnected and/oramalgamated so as to form composite blocks. The joining conduit sectionsmay be arranged to generally reverse the direction of flow along thesaid sections of thermally conductive conduit formation. The conduitsection may be horizontally arranged and situated within or below adrainage basin so as to be submersed in the flow of waste water as asaid first fluid in a said primary conduit that drains from a sanitaryshower facility and to conduct fresh water as a said second fluid towhich heat from the waste water may be transferred.

A further aspect of the invention provides a heat exchanger devicecontaining a conduit formation as set out in the previous aspect of theinvention. The heat exchanger device may have strips or patches ofthermally conductive surface at least partly lining a fluid conduitwhich surrounds and has a face which faces the first sides of saidconduit sections of at least one said series. The conduit sections maybe thermally bridged with the thermally conductive surface via ridges,ribs or spines, which support or mount the conduit sections in the heatexchanger.

A further aspect of the invention includes a formation of a thermallyconductive fluid conduit into sections having three or at least threesides extending longitudinally in an arrangement suitable forincorporation within a heat exchange device for heat transfer between afirst fluid flowing as layers in a primary conduit over the outersurfaces of the said conduit sections and a second fluid flowing withinthe said conduit sections in an overall counterflow directiontransversally to the first fluid flow, characterised in that: thesections are arranged into pairs of layered series whereby the surfacesof one side of the conduit sections of each layer are substantially flatso as to be alignable with a common imaginary geometric surface which isconsistently spaced from one side of a surrounding first fluid conduitsurface of a heat exchange device.

The sections of each series, which may be loops or semi-loops, may bearranged spaced from and in the same geometric orientation as oneanother and may be arranged generally or substantially in a line or row.

Paired layers of conduit sections may be mutually superimposed andoverlapping whereby the sections of one layer or series may beinternested (or interlaced or interposed between) conduit sections ofthe other layer in the pair.

The formation may include several paired said layers located adjacentone another and may, for example, have four layers or series in twopairs or six layers or series in three pairs.

Each paired layer of conduit sections may have an inverted orientationwith respect to its counterpart layer. The surfaces of a second side ofone layer's sections may face a surface of a third side of the otherlayer's sections or vice versa.

Mutually facing surfaces of respective second and third sides ofinterlacing adjacent sections may be consistently spaced from or offsetfrom one another, having like formation and like alignment. The conduitsections may extend longitudinally in a direction that is substantiallyparallel to a common geometric surface of a heat exchanger or the likewith which one side of the conduit sections is alignable or aligned.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be carried out in various ways and a number ofpreferred embodiments of conduit assemblies and heat exchangers inaccordance with the invention will now be described by way of exampleand with reference to the accompanying drawings, in which:

FIG. 1 is a schematic cross section through an example of a shower trayincorporating a preferred conduit assembly and heat exchanger inaccordance with the invention;

FIG. 2 is a schematic cross section through a modified version of theembodiment of FIG. 1;

FIG. 3 shows examples of three further embodiments of conduit assemblyand heat exchanger in accordance with the invention;

FIGS. 4A to 4C show modified versions of the three examples shown inFIG. 3;

FIG. 4D shows an example of an end cap for use in the conduit assembliesof FIG. 3 and FIGS. 4A to 4C;

FIG. 4E shows an example of an end cap segment, as illustrated in FIG.4D, viewed from the perspective of the conduit section ends;

FIG. 4F shows an example of a spacing mesh, which may be used with thevarious embodiments described herein;

FIG. 5 shows a cross section through an extruded triangular conduitsection to be used in series of conduit sections arranged in rows as inFIG. 3 or FIG. 4A;

FIG. 6 is a general view of a shower assembly including the conduitassembly of FIG. 1; and

FIG. 7 shows a schematic view from above of an embodiment similar tothose shown in FIGS. 1 and 2.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 6 shows a general view of a shower tray assembly 100 having ashower head 102, side outlets 104, boiler 106 and shower tray 110incorporating the heat exchanger assembly 108 which is shown in moredetail in FIG. 1. As shown in FIG. 6 water from a fresh water inlet 112may be directed to the shower head 102 and outlets 104 via a pipecircuit 114 via either heating coil 116 in the boiler 106, heatexchanger assembly 108, or both. Recirculation through the heatexchanger 108 may be bypassed by opening a valve 118, flow through theboiler by a boiler flow shutoff valve 120, main shutoff/flow controlvalve 122 may control total output flow. Divert control valve 124 maycontrol proportions of flow to the shower head 102, and side outlets 104and thermostatic control valve 126 may control outlet flow temperature.

Water from the shower head 102 and side outlets 104 falls on to showerfloor top 130, which is circular, then falls down into peripheralchannel 132 before passing under a peripheral lip 134 contiguous withthe shower floor 130 before passing radially inwardly through a primaryflow conduit 136 bounded by upper and lower generally flat surfaces 138,140 before passing over central circular weir 143 and exiting todrainage (not shown) via outlet 144.

While flowing through the primary flow conduit 136, the fluid therein issubject to a cooling heat exchange in which it heats fresh water passingthrough two series (i.e. upper series (or layer) 172 and lower series(or layer) 174) of spiral conduit sections 142.

The spiral conduit sections 142 are arranged as shown in FIG. 7, wherenot all parts are shown for the purposes of clarity. The arrangement, asin FIG. 1, does have therefore relatively central inlets 150 to thesecondary flow conduit sections 142, which are connected by a pipe 152to inlet port 154, as well as a relatively peripheral outlet 156connected by pipe 158 to outlet port 160 as shown in FIG. 7, althoughnot all of these parts are shown in FIG. 1.

Essentially, the flow through the spiral sections 142 in FIG. 1 startsat an innermost pipe section 164 in the lower series that is shown andcontinually loops around and around, in incrementally increasingdiameter, through adjacent spiral loop 168 and so on until final outerloop 170. In this way, heat exchange between the fluid (waste water) inthe primary conduit 136 and the fluid (fresh water) in the secondaryconduit spiral sections 142 is generally counterflow. Flow in theprimary conduit is also generally always at any given local positiongenerally perpendicular to the local section of secondary conduit 142.The secondary flow is split to flow in parallel along an upper series172 and a lower series 174 of conduit sections 142 as envisaged here,with part of the flow passing in a single spiral through all of theupper pipes of the upper series 172 and part of the flow passing inanother single spiral through all of the lower pipers of the lowerseries 174.

As shown in FIG. 1, the conduit sections 142 each have an outer crosssection, which is substantially that of an equilateral triangle. Eachtriangular section has a flat outer wall surface 178, which is spacedfrom and substantially parallel to an adjacent one of the flat upper andlower surfaces 138, 140 of the primary flow conduit 136. Thisarrangement makes it hard for air or contaminants, such as grit orsediment, to accumulate in the primary conduit being horizontallyoriented. Each conduit also has a protruding outer surface portionconsisting of second 180 and third 182 external surfaces (or sides) ofthe triangular cross section. The second and third surfaces meet at acorner 184. The conduit sections 142 in each of the upper and lowerseries can, therefore, be said to be formed in lines or rows, which aregenerally linear in the radial direction. Also, each corner 184 of eachsection extends through an imaginary line between the two corners 184 ofthe immediately adjacent conduit section in the other series 172, 174.Therefore, the conduit series are internested or interlaced with oneanother.

The walls 138, 140 may be slightly curved in which case thesubstantially flat wall 178 may be very slightly curved, either slightlyconvex or concave to follow the curve of the adjacent one of the walls138, 140 but these walls are nevertheless substantially flat in general.

As shown only in part and in dotted lines in FIG. 1, radially extendingupper 190 and lower 192 spacing ribs may be provided, an imaginaryoutline 194 being present in the drawing to show where the dotted linesend in the outwardly radial direction. In reality the ribs 192, 194extend radially fully across the shower floor 130 and they serve both tosupport the shower floor 130 and space and locate the secondary conduits142 inside the primary conduits.

The shower floor 130 may be removable for cleaning purposes, as can theconduit sections 142 and ribs 190,192, if desired.

FIG. 2 shows a modification of the arrangement in FIG. 1 in that thesecond and third sides 180,182 of the conduit section forming theprotruding portion are replaced by a generally part-sinusoidal or bellor hat-shaped protuberance 183.

FIG. 3 shows three other types of conduit cross-sections and how theymay be arranged, aligned and offset with respect to adjacent conduitsections, for the transverse flow of a first fluid in layers above,below and in between the conduit sections. In this embodiment, theconduit sections 142 are all straight and may be extruded or otherwiseformed. Respective ends 200 of the straight pipes 142 may be insertedinto end caps or blocks 202 as shown in FIG. 4D and 4E in order toreverse flow direction. End caps 202 may be arranged such that flowpasses in serpentine (zigzag) fashion separately along each of the upperand lower series (this may make cleaning easy since the series mayeasily be removed separately) or may circulate (loop) up and downbetween the two series at each end cap.

The left hand example in FIG. 3 shows that the corner 184 of the crosssection of the conduit sections 142 may be blunted such that the sectionis trapezoidal. The middle example in FIG. 3 shows how in anothermodification the second face may be outwardly concave and the third faceoutwardly convex. The right hand example in FIG. 3 shows a modificationin which a similar shape is used as in FIG. 2 and wherein an internalsurface 208 of each conduit section is circular so as to resistdeformation under pressure.

FIGS. 4A, 4B and 4C show developments of the respective left-hand,middle and right-hand examples in FIG. 3, wherein internal walls 220 areprovided extending along all of the way inside the conduit sections 142.With the conduit sections formed of material with good heat transferproperties such as copper or an alloy thereof, the internal wallspromote heat transfer between the interior of the secondary conduitsections and the outer surfaces 178, 180, 182 thereof. Internal walls220 also serve to strengthen the secondary conduit sections againstdeformation under pressure.

As shown in FIGS. 5, with triangular secondary conduit sections 142 theinterior walls 220 may split the secondary conduits into multipleinternal channels 230 extending all of the way therealong, for examplesix (FIG. 5) or nine channels. The first wall 178 as shown here issupported and spaced from the adjacent primary conduit wall 140 byridges or ribs 192 on the primary conduit wall aligned with thedirection of primary fluid flow. The sections shown can conveniently beproduced by extrusion, e.g. of metal or metallic alloys such as copper,aluminium or their alloys. Each interior channel 230 may, as shown inFIG. 5, communicate directly through a single outer wall section 232 tothe outer wall surface of the conduit section 142, thereby giving eachchannel 230 good heat transfer access to the exterior thereof. Eachconduit section may include a centre point 234 defined by a join of aplurality of generally straight wall portions 236.

In the embodiments of FIGS. 3 to 5, which have straight conduit sections142, the shower tray associated therewith may be generally rectangularwith a central or edge drain channel (not shown), with overallconfiguration bearing some resemblance therefore to that shown in FIGS.10 to 12 of WO2009/1011671 (Gilbert). The number of rows of conduits ineach series of conduit sections may be chosen to suit each particularapplication. Some embodiments may, for example include between about 15and 30 conduit sections in each series.

Although the series may be paired as shown in FIGS. 1 to 4C, a second orthird pair of conduit series may be used in other embodiments, each pairrunning generally parallel to the others. Ones of said substantiallyflat surfaces 178 of the conduit sections 142 may in these cases bearranged spaced from and substantially parallel to one another with asimilar spacing therebetween to that between the conduit sections 142and the upper 138 and lower 140 wall surfaces of the primary conduit136.

In the various embodiments herein, similar components have been givensimilar reference numerals. In FIGS. 3 and 4A to 4C, although the upperand lower surfaces 138, 140 of the primary conduit 136 have been shownin line with the substantially flat surfaces 178 of the conduit sections142, in practice there are slight gaps between the surfaces 138, 140 andflat surfaces 178 of the conduit sections 142 as shown in FIGS. 1 and 2.

As shown in FIG. 4F, a mesh or net 400 may be provided having mutuallyparallel thick cords 402 and mutually parallel thin cords 404, which runacross to the thick cords 402. The thick cords 402 may be about 0.6 to1.0 mm or 1.5 thick. The thin cords are thinner. The mesh 400 may beplaced between the upper series of conduit sections and the lower series(and between the upper series and the upper surface 138, and between thelower series and the lower surface 140) and may flex into position asthe two series are drawn towards one another during assembly. The meshmay be positioned with the thin cords 404 normal to the general flowdirection through the primary conduit and thick cords generally parallelthereto. The thick cords serve as spacers for the secondary conduits andfor supporting the shower floor 130 so that weight thereon does notdisadvantageously reduce the gaps between the various components andaffect flow adversely. The thin cords, however, allow flow to passthereby and serve to promote turbulent flow and therefore good heattransfer. It will be understood that the mesh may have differentconfigurations dependent upon the configuration used for the conduitsections, such that the thick cords may remain locally aligned with thegeneral flow direction and the thin cords normal thereto. For example,with spiral-shaped conduit sections 142 as in FIGS. 1 and 2 hereof, thethick cords 402 may be generally radially arranged and the thin cords404 may be generally arranged in spirals or circles.

Further discussion of the embodiments now follows. In each of thedescribed embodiments, a thermally conductive conduit formation orassembly is arranged as a succession or series of sections or loopswithin a device for counterflow heat transfer between a fluid flowingwithin conduit sections of the conduit assemblies and a fluid flowing aslayers of generally consistent thickness in a primary flow conduit, thisflow being transversally across or obliquely crossing over or passing inbetween said conduit sections. The direction of flow of the first fluidlayers in the primary conduit may (at any given point) be substantiallyor fully perpendicular to the direction of second fluid flow in theconduit sections (as seen from a point of view normal to a commongeometric surface, such as a generally flat or slightly curved innersurface of the primary conduit) or the generally planar orientation ofthe overall heat exchanger device, or at a given or variable angleobliquely crossing over the secondary fluid conduit sections. Overall,through the heat exchanger, the respective flows in the primary conduitand second conduit sections in preferred embodiments interact in acounter-current manner for counterflow heat exchange therebetween.

The layered flow of the first fluid (which may be generally laminar orturbulent) in the primary conduit is intermittently divided intoseparate layers as it passes passing by each secondary fluid conduitsection on each of both sides (above and below) that reconnect intemporary confluence between successive conduit sections.

Outer layers of the fluid flow in the primary conduit is in a relativelystraight and direct path in the gap between flat sided surfaces of thesecondary conduits and enveloping sides of the primary conduit.

An inner layer of first fluid in the primary conduit flows in arelatively longer undulating flow path between mutually facing secondand third sides of the secondary fluid conduit sections.

Heat exchange device implementations with more than one pair of layersof secondary fluid conduits are envisaged and will also have one or moreinner layers flowing directly straight between mutually spaced andfacing flat sides of the secondary fluid conduit sections.

A locally regulated distance between the facing sides of the secondfluid conduit sections and the enveloping primary fluid conduit surfaceis established so as to provide a substantially uniform distribution ofheat transfer through all exposed surfaces of the thermally conductivesecond fluid conduit. This may take into consideration all relevanttechnical factors, including: the frictional resistance to first fluidflow in the primary conduit induced by the conduit surfaces of theconduit sections; the viscosity of the first fluid in the primaryconduit, and variations resulting from temperature changes; the crosssectional area of the first fluid flow front in the primary conduit;and/or resistance to first fluid flow in the primary conduit induced bylocal bends in the layered flow's flow path therein.

In some embodiments, the outer or straight-flowing layer gaps orspacings next to the interior surfaces of the primary conduit may besmaller than the inner or undulating layer gaps or spacings. Optimaldistances may in some preferred embodiments be determined throughexperimentation or the testing of computational models with fluiddynamics simulation software, such as CFD or EFD programs.

The term “consistent” in reference to conduit gaps, offsets or spatialarrangements may in some preferred embodiments refer to constancy oruniformity that is consistently related to the constancy or variation ofthe technical factors with which it may be related, and these may notnecessarily be always constant.

For example, the spacing between facing conduit sides (or the firstfluid flowing layer thickness in the primary conduit) may increase incorrespondence to: a narrowing in width of the layers (or first fluidcross sectional flow front); a decrease in temperature of the firstfluid; an abrupt change in local flow direction or a turbulent juncture;and/or a decrease in the exposure to heat exchange surface area. Thesefactors may combine in such a way as to negate or promote each other tosome degree, so the consideration of each and any of these relationshipsshould not be taken so absolutely as to not consider it in relation tothe influence of other factors.

The juncture between second and third longitudinal sides/faces of eachconduit section opposite a first longitudinal side/face thereof may beselected from a variety of shapes, such as rounded, filleted, beveled orindented. In some embodiments, a fourth side or longitudinal face may bepositioned and uniformly offset from the enclosing surface of thelayered fluid conduit and in some embodiments the conduit section maythereby have a trapezoidal cross section. This juncture or fourth sidemay be substantially narrower than the first side and spaced furtherapart from the enclosing fluid conduit surface of the primary conduitthan the corresponding first side to allow for the combined passage offluid layers coming from (or going to) both the equivalent second orthird sides and the first side of an adjacent conduit section, whichthereat converge and/or diverge and may blend.

Preferred embodiments have particular application within a flat devicefor the recovery of heat from wastewater draining from sanitary showershaving substantially flat surfaces of the primary conduit surroundingthe secondary conduit sections. The substantially flat primary conduitsurfaces may be horizontal or slightly inclined, substantially planar orslightly curved, and may be arranged together with the secondary conduitsections for near co-planar (i.e. having alignment within: a commonplane; a nearby parallel plane; a nearby nearly parallel plane; or agenerally/nearly parallel nearby nearly planar surface, e.g. slightlydomed, humped or conical) countercurrent flow of the two fluids withinthe same general planar zone, which may comprise in some embodiments aregion bounded by two nearby parallel planes or a region in the vicinityof all of a number of near co-planar surfaces.

The conduit formations or assemblies described in the embodiments hereofmay be employed with general applicability in broader contexts beyondthe scope detailed above wherein each conduit section sequence isaligned with non-planar surfaces which are offset one from another, suchas in helical formations aligned with concentric cylindrical, prismaticor frustrumatic surfaces.

Thus, notwithstanding the attributes appropriate for a conventionalshower basin context, the invention may also be applied in embodimentshaving heat-exchanging conduit sections arranged in non-planar formssuch as a dome, cone, pyramid, frustum or indeed any other (preferablysymmetrical) primary conduit surface formation.

It is not always necessary for the secondary conduit sections to conformentirely to the characteristics and attributes outlined herein. Forexample, if a significant part of the second fluid conduit (and/or theprimary fluid conduit) in a heat exchange device has the determiningcharacteristics of this invention, its effectiveness will not beundermined, only that it may be limited proportionally to that part.Therefore, the terms “sections of conduit” and “surfaces of a side ofconduit sections” or words to such an effect of meaning may be taken torefer only to those sections or surfaces of the conduit having thecharacteristics and attributes described.

Further, in some embodiments, the cross sectional shape of the secondaryconduit sections may incrementally change in the relative dimension ofits sides or parts or in its shape, even morphing from one type of shapeto another along the length thereof.

The paired layers or series of secondary conduit sections may beparallel with regularly spaced conduit sections along the series (i.e.along the general direction of flow in the primary conduit) in someembodiments, such as those shown in FIG. 1, FIG. 3, FIGS. 4A to 4C, and5, or may have incrementally converging conduit sections along theseries in other embodiments (such as that shown in FIG. 2), by virtue ofthe nature of the cross-sectional shape or according to factorsdescribed above.

The pressure of the fluid flowing within the secondary conduit sectionsmay generally be substantially greater than that of the first fluid, andmay in certain formations tend to promote temporary distortion of thecross-sectional shape, which may change irreversibly if excessive. Theseshape distortions, if allowed to develop, could have a detrimentaleffect upon the appropriate functioning of the device and are normallybest avoided. Thus, some embodiments may employ a natural variation ofthe intended shape that becomes more appropriate when distorted underpressure. This for example may take the form of concave sides instead offlat sides, which may become more like flat surfaces in operation.

The description of shapes defined in the claims therefore do notnecessarily refer to the natural or unstressed shape of the conduit butmay refer to a shape that the conduit may adopt under the stress ofoperational fluid pressures. To support high secondary fluid pressureswell, embodiments of this invention may have a variable conduit wallthickness or have one or more circular interior tubes carrying the fluidinside the external surface shape (such as the right-hand example shownin FIG. 3). Such a section, including interior tubes, may be extrudedinto the desired shape or made from conventional tube parts with weldedor attached corner ridges forming the outer walls of the secondaryconduits that may be made of the same material or a thermally conductivecomposition different to that of the tube(s).

Taking advantage of modern industrial techniques, the thermal transferconduit may alternatively be an extruded polymer with thermallyconductive additives or insets (e.g. metallic fibers) to thermallybridge the inner and outer surfaces of the conduits. The addition ofmetallic granules as an additive to the polymer, which aggregatepredominantly at the extruded conduits' surfaces, also promotes theappropriate distribution of heat more evenly over the conduits' surfacesto where it may more effectively transfer to/from the fluid.

As already described, the heat transferring conduits of this inventiondo not require any necessary correspondence of shape between the innerand outer sides, as seen in the cross-section. Thus, the interior ofeach secondary conduit may in some embodiments of this invention beadvantageously fragmented (as shown in FIGS. 4A to 4C and 5), so as toincrease the surface area available for heat transfer with the fluidflowing within (without extending the devices overall dimensions) andrender the outer surface more resistant to shape distortion under highdifferences of fluid pressure across it. In this instance, the heattransfer conduit's passageway and the fluid flowing within it will alsobe correspondingly fragmented, as illustrated in FIGS. 4A to 4C, and 5,due to the presence of internal walls longitudinally aligned along andwithin the conduit sections which extend across and separate the overallcross sectional area into separate enclosed portions. Heat transferringconduits having such cross sectional shapes with fragmented passageways,such as those shown in FIG. 5 can be made by an extrusion process fromcopper, aluminium or an alloy such as brass or aluminium alloy whicheffectively distributes the internally absorbed heat to the outersurface of each conduit section by virtue of its excellent thermalconductivity.

Conduit surfaces may advantageously be coated or plated with a materialdifferent to the extrusion material (e.g. copper on aluminium). Theextruded conduit section may be subsequently curved to formappropriately shaped sections as particular embodiments of the heatexchange device require, such as the spirals like those of theembodiments of FIGS. 1 and 2.

Whilst the conduit sections may be identically shaped with identicalcross-sections, in other embodiments the shape of the sections maychange gradually or incrementally along the series without substantiallyaffecting the regular offsetting or spacing of the secondary conduitsections from the primary fluid conduit surfaces for uniformly layeredflow therethrough.

To enhance the heat transfer available to the surrounding fluid theouter surfaces of the conduit sections and/or the primary flow conduitmay be treated, scored, grooved and/or undulated. Scores, grooves orundulations (not shown) may be formed extending transversely to,obliquely to or in alignment with the local direction of fluid flowthrough the primary conduit. An alternative, with high performance inavoiding the accumulation of grime, fouling or bio-slime, is to lineconduit-supporting ribs or battens (of and in the enclosing primary flowfluid conduit) with a thermally conductive surface, which extends alongthe surrounding (counter-facing) surface that is offset from the firstside of each secondary conduit section. The thermally conductivesurfaces around each rib supporting a single section of secondary flowconduit may in some embodiments be inter-connected with adjacent ribsections along (i.e. in the direction of) the section of second flowconduit but should preferably not be thermally interconnected withadjacent rib sections supporting the adjacent parallel sections ofsecond flow conduit, so as to avoid substantial dissipation of thethermal gradient that incrementally progresses along the series ofsecondary flow conduit sections.

Additional embodiments of conduit assemblies in accordance with theinvention may comprise or be used as part of low height heat recoverydevices for the transfer of heat from warm wastewater flowing in adrainage system under gravity to fresh water. Thus, such embodiments inaccordance with the invention may be used as or as part of heat exchangedevices for installation within or under the drainage basin of sanitaryshowers.

In some additional embodiments, the conduit surfaces may be coated witha surface treatment or layer of material (eg copper over aluminium), toresist fouling, microbial growth and/or corrosion.

Outer surfaces of the conduit sections may feature indentations orgrooves where wall is thickest (eg. at corners or between passagewaysformed by internal walls inside the conduit sections), the indentationsor grooves advantageously increasing the surface area available for heatexchange and/or enhancing turbulent flow so as to provide better heattransmission). Additionally, the indentations or grooves may provide afeature with which a protrusion on the surrounding primary conduitsurface can couple or attach for structural stability.

Outer surfaces of the conduit sections may have indentation features,cuts or holes (e.g., screw holes formed in flanges formed thereon) atone or more positions along their length. These may be arranged to fitor complement a protrusion/protruding feature on or attached to asurrounding primary conduit surface to provide good structuralstability.

Outer surfaces of the conduit sections (which may be triangular orsubstantially triangular in cross section) and/or the counter-facingsurfaces of a surrounding primary conduit surface may have ridges,protrusions or shallow formations to enhance fluid mixing or turbulentflow (for better heat transfer), e.g. chevrons. The chevrons may bealigned with flow through the primary conduit, such as by having a sharpend thereof pointing in an upstream direction.

While the flow in the primary conduit is often described as in layers,the layers in some embodiments may be fragmented or merely substantiallylayer-like, for example if one or more of the surfaces of the conduitsections and the primary conduit surrounding the flow is fluted and/orif there are spacers (e.g. to space and locate the conduit sectionswithin the primary conduit) or walls/flow-fences or turbulence-formingfeatures within the flow space in the primary conduit which fragment thelayer.

In some embodiments strings, lines (for example of polymer) or a seriesof webs, straps or mesh may be employed within the primary flow conduitand/or between the conduit sections. These may be sandwiched between theconduit surfaces to transmit weight loads and maintain the optimalspacing and/or promote fluid turbulence. The spacing may typically be0.6-1 mm, although different minimum spacing between surfaces within theprimary conduit (including between the conduit sections) may be appliedin some other preferred embodiments. In some further embodiments, a meshfor this purpose may have first lines substantially aligned with theflow and acting as spacers cross linked with second lines which may begenerally transverse to the flow to create turbulence and, in this case,the second lines may be thinner than the first lines so that they allowflow past themselves.

It is envisaged that various changes may be made to the embodimentsdescribed without departing from the scope of the invention as definedin the accompanying claims.

1. A thermally conductive conduit assembly mountable in a primary flow conduit of a heat exchanger, the conduit assembly comprising: a first series and a second series of elongate conduit sections, the first and second series Being arranged next to one another such that each series extends in a series direction generally transverse to the conduit sections, each conduit section in the first series having at least a portion along the length thereof which has a cross section having on a wide side of the conduit portion a substantially flat first wall which is substantially aligned with the series direction, the cross section also including a protruding wall formation in the conduit portion extending towards a corner on a narrow side of the conduit portion located opposite the wide side and being interested between conduit sections of the second series, with the substantially flat wall substantially coincident with a general flow direction of said primary flow conduit.
 2. A heat exchanger assembly, comprising the conduit assembly as claimed in claim 1 mounted inside a primary flow conduit having a general flow direction therethrough, which is coincident with the substantially flat wall, the conduit assembly and the primary flow conduit being arranged for heat transfer between respective fluids therein.
 3. A heat exchanger assembly, comprising: primary flow conduit having a general flow direction therethrough; and a conduit assembly mounted in the primary flow conduit, the conduit assembly including a first series and a second series of elongate conduit sections, the first and second conduit series being arranged next to one another in rows extending in a direction generally transverse to the conduit sections and coincident with the general flow direction through the primary conduit, each conduit section in at least the first series having at least a portion along the length thereof which has a substantially flat wall which is substantially in line with a substantially flat wall of one or more adjacent conduit sections in the same series in the general flow direction through the primary flow conduit.
 4. The assembly as claimed in claim 3, wherein the conduit sections in the second series each have at least a portion along the length thereof which has a cross section having on a wide side of the conduit portion a substantially straight first wall which is substantially aligned with the series direction, the cross section also including a protruding wall formation in the conduit portion extending towards a corner on a narrow side of the conduit portion located opposite the wide side and being interested between conduit sections of the first series, with the substantially straight wall substantially coincident with a general flow direction of said primary flow conduit.
 5. The assembly as claimed in claim 4, wherein the first and second series have general orientations opposing one another, the orientation of each being in common with the orientations of the protruding formation with respect to the wide side of each of their respective conduit sections.
 6. The assembly as claimed in claim 4, wherein the conduit sections of the first series are interested with conduit sections of the second series.
 7. The assembly as claimed in claim 1, wherein the conduit sections of the first and second series each have a second and a third side with external walls thereof shaped and arranged in such a way that: the second side walls of the first series complement the third side walls of the second series; and the second side walls of the second series complement the third side walls of the first series; so as to generally provide a substantially consistent gap for the passageway there between of a layer of fluid having generally a thickness which is not substantially varying thereat.
 8. The assembly as claimed in claim 1, Wherein the first and second conduit sections are straight.
 9. The assembly as claimed in claim 1, wherein the conduit sections are curved.
 10. The assembly as claimed in claim 1, wherein the protruding wall formation comprises two generally flat wall portions such that said cross section is substantially triangular.
 11. The assembly as claimed in claim 1, wherein the protruding wall formation is substantially symmetrical about a line substantially perpendicular to the substantially flat first wall.
 12. The conduit assembly as claimed in claim 1, wherein the substantially flat first walls of the first and second conduit sections are generally horizontally arranged.
 13. The assembly as claimed in claim 1, wherein said first and second conduit sections each have internal walls extending therealong.
 14. The assembly as claimed in claim 3, Wherein the primary flow conduit has an internal wall portion adjacent to, spaced from and substantially aligned with the substantially flat wall of one of the first or second series of elongate conduit sections.
 15. The assembly as claimed in claim 14, wherein the internal wall is flat in one or more portions thereof and is parallel to the substantially flat walls of the one of of said first and second series of elongate conduit sections which is adjacent to the internal wall.
 16. The conduit assembly as claimed in claim 1, wherein the conduit assembly is further mountable in the heat exchanger, which includes an elongate conduit section having an internal wall extending therealong, such that the elongate conduit section acts as a heat flow bridge from fluid in the conduit section to an external wall of the conduit section.
 17. The conduit assembly as claimed in claim 1, wherein the conduit assembly is further mountable in the heat exchanger, which includes at least two adjacent conduit surfaces arranged for fluid flow therepast in a fluid flow direction, and wherein the conduit assembly further includes at least one flexible elongate spacing member located between at least one of the conduit surfaces and the conduit assembly to define a space therebetween.
 18. The conduit assembly as claimed in claim 17, wherein the flexible elongate spacing member is part of a mesh, the mesh including a plurality of said flexible elongate spacing members which are interconnected by joining members.
 19. The conduit assembly as claimed in claim 17, wherein said at least one flexible elongate member is generally aligned with a said fluid flow direction.
 20. The conduit assembly as claimed in claim 18, wherein said joining members are elongate lengths of material and are thinner than said at least one flexible elongate spacing member.
 21. The conduit assembly as claimed in claim 1, wherein the first and second series of elongate conduit sections are thermally conductive conduit sections and are extrusions composed substantially of copper or aluminium.
 22. The conduit assembly as claimed in claim 21, further including at least one components made of plastic or resin and interconnecting thermally conductive conduit sections at respective ends thereof.
 23. The heat exchanger assembly as claimed in claim 3, wherein the primary flow conduit and conduit sections are mutually arranged for counterflow heat exchange generally between a primary flow passing through the primary conduit and a secondary flow passing through the thermally conductive conduit sections.
 24. The heat exchanger assembly as claimed in claim 3, wherein the heat exchanger assembly is positionable within a shower facility. 